DESCRIPTION: The long-term goal of the applicant's research is to understand how humans adapt to vestibular disorders with the practical aim of developing better physical therapy programs for patients with vestibular disorders. The specific objective of this proposal is to learn more about the mechanisms underlying short-term (minutes to hours) VOR adaptation in normal humans. The emphasis is upon adaptive control of 1) otolith-ocular reflexes, 2) the phase of the canal and otolith-ocular reflexes, and 3) the torsional VOR. The applicants will evaluate the error signals, contextual cues, and any preprogrammed responses that lead to the expression of adapted VORs. Relatively little is known about these aspects of vestibular physiology and each potentially bears on important issues related to vestibular adaptation, the error signals that drive it, and how adaptive compensation might be promoted in patients.